The new search interface Google had been testing in beta since last fall finally has a broad release. Users will see it roll out globally across 37 languages today, along with an English language mobile version for the US.

On the mobile side, the changes are essentially the same as on the desktop. The only problematic bit seems to be that when you expand your search options, the results are pushed halfway off the display:

You can just pan back and forth, but that may end up costing however much time you've saved with the new search features int he first place.

Meanwhile, Bloomberg Businessweek has an in-depth look at how Google arrived at the changes. What started as hundreds of potential new results pages from a team of designers was whittled down gradually, for stylistic and technical reasons, to a page ready for internal testing in October of 2009. That testing was supplemented by 19 hour-long eyetracking sessions for fine-tuning:

During eyetracking, the engineers and designers sat in an adjoining room and gawked through a two-way mirror while users tried out various incarnations of the new search results page. Each participant was given prescribed tasks to search for so that the Google team could see the page in action... When users got distracted... or failed to grasp how they were intended to interact with the page, it meant it was time to scrap an idea.